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PubMed1987

Elimination of the gametocytes of Theileria annulata of cattle by primaquin phosphate.

Calves were experimentally infected with Theileria annulata and five drugs were administered in an attempt to exterminate the gametocytes of the parasite. The results of the experiment proved that primaquin phosphate is an effective parasiticide. The gametocytes from 30 calves treated with primaquin phosphate were exterminated completely. A further eight calves were treated with sulfamethoxypyrazine, trimethoprim, naganin and acaprin, but these drugs were not found to be effective in eliminating the gametocytes. The phase, size and colour of the gametocytes in these calves were the same as those of the four untreated control calves.

Animals↗

PubMed1987

Immunization against East Coast fever: the use of selected stocks of Theileria parva for immunization of cattle exposed to field challenge.

Two antigenically different stocks of Theileria parva parva (Kilifi and Marikebuni), previously characterized as belonging to groups A and C respectively on monoclonal antibody (MAb) profiles, were selected for immunization of different breeds of cattle against East Coast fever (ECF) by the infection and treatment method. A total of 52 immunized cattle and 33 susceptible controls of different group sizes were exposed to field challenge by ticks for periods of 42-90 days at three field sites where ECF is endemic on the Kenyan coast. All immunized cattle survived ECF challenge, but 87% of the controls died of the disease. The cattle exposed at one site had been immunized 1 year earlier and maintained tick-free in the intervening period. The level of immunity in these cattle was similar to that of cattle which had been immunized 1 or 2 months prior to exposure. Thus, immunity had not waned over the 1-year period. A study at another site showed that acaricidal treatment of immunized cattle could be safely extended from twice a week to once every three weeks, whereas in susceptible cattle even twice weekly spraying did not control ECF. The isolates made from infected controls during the trials indicated the presence of three T. p. parva stocks as defined by MAb profiles. Of the two stocks used for immunization, T. p. parva Marikebuni induced broader protection. In view of the apparent limited antigenic diversity of T. p. parva strains within the Coast Province it is suggested that the Marikebuni stock might represent a key stock for vaccination in this area.

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PubMed1987

Immunization of neonatal bovines against Theileria annulata by an infection and treatment method.

Sixty three cross-bred (Bos taurus X Bos indicus) 4-5-day-old calves were divided into 16 groups (A-P). Each calf in Groups A and B was given ground-up-tick supernate prepared from Theileria annulata-infected or non-infected Hyalomma anatolicum anatolicum (GUTS) equivalent to 5 ticks (50 infected acini). Groups D and E received infected GUTS equivalent to 2 ticks (20 infected acini) and Groups G and H were given infected GUTS equivalent to 1 tick (10 infected acini). Each calf in Groups J, K and L received infected GUTS equivalent to 5 infected acini (0.035 tick), and Group O was inoculated with non-infected GUTS equivalent to 5 ticks. Each calf in Groups A, D, G, J, K and O was also given a single intramuscular injection of long acting oxytetracycline, 20 mg kg-1 body weight just after inoculation of GUTS. Severe reactions resulted in the death of five of eight, three of eight, five of six, one of five and one of five calves in Groups A, D, G, J and K respectively and all of the calves in Groups B, E, H, and L. The surviving calves of Groups A, D, G, J, K and O were challenged on Day 45 post-immunization along with freshly introduced susceptible control calves of Groups C, F, I, M, N and P. All the calves of Groups A, G, J and K withstood the challenge dose; in Group D four of five and in Groups C, F, I, M, N, O, and P all the calves died of theileriosis. It is concluded that though the infection and treatment method of immunization may be used for neonatal bovines, the dose of immunogen should be based on actual counts of infected salivary acini of ticks instead of the number of ticks.

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PubMed1987

Cross-reaction among four isolates of Theileria annulata from India.

A close identity in virulence and cross-protection of four isolates of Theileria annulata was observed when infection was produced in naive, crossbred (Bos taurus male X B. indicus female) male calves. The evidence that strains of T. annulata in India differ in virulence and immunogenicity is equivocal at present.

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PubMed1987

Relationships between Cytauxzoon felis and African piroplasmids.

A cat which had recovered from Cytauxzoon felis infection following treatment with the anti-theilerial drug, parvaquone, showed an increase in piroplasm parasitemia after splenectomy and its blood was suitable for the preparation of antigen smears for the indirect fluorescent antibody test. High levels of antibodies were found in this cat after recovery, in two other cats sub-lethally infected with piroplasms and in sera of naturally infected bobcats. Cats recovered from piroplasm infection died from cytauxzoonosis when challenged with organ material containing C. felis schizonts. Tests with piroplasm antigens and positive sera of C. felis, South African Babesia felis and African Theileria taurotragi showed no significant serological relationship between C. felis and the African parasites. C. felis was not shown to be infective for splenectomized sheep.

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PubMed1987

Effect of timing and intensity of challenge following immunization against East Coast fever.

When groups of Theileria parva parva Muguga-immunized cattle were given a homologous lethal challenge at different times after immunization, it was found that 4/6, 5/6, 6/6 and 6/6 animals survived when challenged on Days 5, 10, 20 and 30, respectively, post-immunization. With a heterologous challenge (T.p.parva Marikebuni), 2/6, 5/6, 4/6, 4/6 and 5/6 cattle survived when challenged on Days 5, 10, 20 and 30, respectively, after immunization. All controls, except one, died of East Coast fever (ECF). The survivor underwent severe ECF and recovered after a prolonged convalescence. When two T.p.parva Muguga-immunized animals were each given homologous challenge by application of 1000 infected ticks (infection rate of 20 infected acini (i.a.) per tick), both survived a mild ECF reaction. When groups of T.p.parva Muguga- or T.p.parva Muguga/Marikebuni-immunized cattle were challenged with different doses of T.p.parva Muguga sporozoites (equivalent of 140, 1400 and 14,000 i.a. per animal), 28/29 cattle survived. All controls died of ECF. It was concluded that cattle could be safely exposed to tick challenge 1 week after immunization by infection and treatment using appropriate immunizing stock(s). Massive homologous challenge did not break through the immunity induced by the immunization procedure.

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PubMed1988

Isolation and characterization of bovine Theileria parasites in Zimbabwe.

Theilerial parasites of cattle were isolated by a variety of methods from the Harare area of Zimbabwe. Parasite stocks were established in lymphoid cell cultures and as cryopreserved sporozoite stabilates in the laboratory. Fourteen stocks in culture were characterized by testing them with monoclonal antibodies (MAb) raised against T. parva parva and T. parva lawrencei antigen. Two of these stocks had profiles similar to T. taurotragi isolates from East Africa, the other stocks had profiles similar to T. parva parva, however, many of them failed to bind MAb No. 7, and this may be a distinctive feature for T. parva bovis. Three T. p. bovis stocks were titrated by injecting different doses of the respective stabilates into pairs of cattle. Reactions ranged from severe to inapparent according to the stocks and dose used, but no fatal reactions were recorded, even at the highest dose rate. On recovery, all cattle were given homologous and then heterologous challenge. The results of the latter challenge showed that the Boleni stock gave good cross-protection against challenge with two other Zimbabwean stocks. This stock may therefore be a candidate for immunizing cattle, under field conditions, to protect them against T. p. bovis in Zimbabwe. Non-pathogenic strains of T. p. bovis may be difficult to distinguish from T. taurotragi unless cross-challenge experiments can be conducted and/or MAb profiles have been made. An improved serological test is needed to differentiate antibodies to these parasites in the sera of recovered cattle.

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PubMed1988

Preparation of monoclonal antibodies to Theileria sergenti and their reactivity to antigens in experimentally infected cattle.

Two distinct monoclonal antibodies (3-H and 11-D) were produced against Theileria sergenti. These two new products, together with monoclonal antibody 1-G obtained in a previous study, were used to detect the parasites in experimentally infected cattle. During the first period of dexamethasone treatment, which was carried out to increase parasitemia in the infected cattle, the number of erythrocytes detected by 3-H, 11-D and 1-D increased in two experimentally infected calves. During the second period of dexamethasone treatment, the number of infected erythrocytes detected by 3-H and 11-D were similarly increased, but the number of infected erythrocytes detected by 1-G did not increase and infected erythrocytes in one calf were not detected by 1-G.

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PubMed1988

Morphology and transmission of Theileria recondita (Theileriidae: Sporozoa) isolated from Haemaphysalis punctata from north Wales.

Adult Haemaphysalis punctata (Canestrini and Fanzago 1877) collected from an area of rough grazing at Mynydd Mawr, Aberdaron, North Wales, transmitted Theileria recondita (Wales); field-collected nymphs failed to transmit this parasite. Following adult tick infestation, piroplasms were first observed in the blood of splenectomised infested sheep 8 days after tick attachment; the parasitaemia lasted 9 days. The parasite can also be transferred by syringe passage of blood from splenectomised to normal sheep and vice versa. Parasitaemias were higher and of longer duration in splenectomised animals. A rise in parasitaemia was detected in a splenectomised ewe after parturition, 19 months following blood-transmitted infection from which it had recovered clinically. The morphometrics of the piroplasms of T. recondita (Wales) were investigated; the rod and the ring forms were the most common. The mean length of the rod form was 2.09 microns and the mean diameter of the ring form was 1.22 micron.

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PubMed1988

Pathogenesis of infection with Theileria recondita (Wales) isolated from Haemaphysalis punctata from north Wales.

The pathogenicity of Theileria recondita infection in both splenectomised and non-splenectomised sheep was investigated. Following transmission of T. recondita to splenectomised animals both by adult ticks and blood transfusion a fever and severe macrocytic hypochromic anaemia developed which lasted the 9 days or more of patent infection. The prepatent period following tick attachment was about 8 days, but was variable following blood transfusion. Infection of normal animals caused a transient macrocytic hypochromic anaemia and slight fever which lasted throughout the period of low parasitaemia (7 days). The increase in mean cell volume was due to an increase in numbers of juvenile red cells in the peripheral blood. There was a transient neutrophilia and lymphocytopenia but no significant changes in thrombocyte or leucocyte numbers.

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PubMed1988

The effect of the host lymphocyte lysosomal system on the developing intracellular Theileria annulata sporozoites.

The fate of developing intracellular Theileria annulata sporozoites within bovine peripheral blood lymphocytes (PBL) was investigated in vitro using acid phosphatase ultracytochemistry. The intracellular sporozoites, while they developed into trophozoites, fed, and transformed into schizonts, provoked intense host lysosomal activity as early as 30 min after they were mixed with lymphocytes. Although viable developing trophozoites failed to fuse with lysosomal vesicles, thereby avoiding enzymatic digestion, the dead parasites readily formed 'phagolysosomes', resulting in lysosomal degranulation and trophozoite digestion. Possible factors responsible for the observed lack of lysosomal fusion with viable trophozoites are discussed.

Acid Phosphatase↗

PubMed1989

Relative role of male and female Hyalomma anatolicum anatolicum ticks in Theileria transmission.

The relative role of male and female Hyalomma anatolicum anatolicum ticks in the epidemiology of Theileria transmission was studied by detecting Theileria sporozoites in the dissected salivary glands of 568 ticks by the methyl green pyronin staining method. Detailed frequency distribution of Theileria-positive acini in the salivary glands of the 264 (46.48%) positive ticks from a field collection in Haryana indicated that the number of infected salivary acini per positive tick was greater in females than in males. This suggests that female ticks have a more important role in Theileria transmission than male ticks. This finding assumes greater significance in the light of the observation that the natural male:female ratio is also in favour of female ticks.

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PubMed1989

Immunization of cattle with a Theileria parva bovis stock from Zimbabwe protects against challenge with virulent T.p. parva and T.p. lawrencei stocks from Kenya.

Following inoculation of 34 Bos indicus (Boran) cattle with a Theileria parva bovis (Boleni) stock from Zimbabwe, 18 animals underwent mild theilerial reactions, 12 underwent moderate reactions, three suffered severe reactions and one died. When these animals were subsequently challenged with different virulent stocks of either T.p. parva (Muguga, Marikebuni or Mariakani) or T.p. lawrencei (Ngong 1 or Nanyuki) from Kenya, all except two animals resisted challenge. The two reactors were part of the group challenged with the T.p. parva (Mariakani) stock. All 12 susceptible control animals underwent severe reactions and 11 died. The results of these experiments suggest that T.p. bovis (Boleni) may be used in some situations to immunize cattle against East Coast fever without the need to provide concomitant chemotherapy as in the infection and treatment method of immunization.

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PubMed1989

The effect of dose and line on immunisation of cattle with lymphoblastoid cells infected with Theileria annulata.

Thirty-one Friesian calves in Morocco susceptible to tropical theileriosis were protected against a lethal sporozoite challenge by prior infection with lymphoblastoid cell lines infected and transformed in vitro by a Moroccan stock of Theileria annulata. The challenge infection of cryopreserved sporozoites killed all four susceptible control calves within 20 days. Four schizont-infected cell cultures at Passage 3 were inoculated at four different doses, 10(8), 10(6), 10(4) and 10(2), into pairs of calves. The recipient animals showed great variation in severity of disease symptoms, which did not show a linear correlation with the cell dose inoculated. The most severe disease symptoms were recorded, prior to challenge, in the 10(2) cell dose recipients; one animal died of acute theileriosis and another had to be treated. One of the four cell lines used was more virulent than the other three. Two years after the completion of this experiment, immunised animals have shown normal productivity traits.

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PubMed1989

Soluble antigens from culture-grown Besnoitia besnoiti endozoites.

Soluble antigens from Besnoitia besnoiti cell culture-grown endozoites, obtained either by hypotonic lysis or by freeze-thawing and ultrasonication (FTS) of the organisms, were detected by the agar gel immunodiffusion method. Each antigenic preparation yielded 1-4 precipitin lines when reacted with the corresponding rabbit hyperimmune serum, while no reaction was observed with Besnoitia-positive sera from naturally infected cattle. Soluble exoantigens released by viable Besnoitia endozoites into the supernatant of infected cell cultures formed two precipitin lines with rabbit anti-FTS hyperimmune serum and appeared as positively charged protein in immunoelectrophoresis. The precipitin lines observed were parasite specific since no reaction occurred with either lysates of normal Vero cells or with supernatants from non-infected cell cultures.

Animals↗

PubMed1990

Immunization of cattle against Theileria parva bovis and their exposure to natural challenge.

Theileria parva bovis isolates were tested for their immunizing capacity under natural field challenge on Willsbridge Farm in the highveld of Zimbabwe. Fifteen susceptible Sussex yearlings were immunized with the Boleni stock and 15 with a mixture of three isolates from the farm, using tick-derived sporozoite stabilates. No chemoprophylaxis was used. A dose of 0.1 ml of stabilate appeared to be safe in preliminary laboratory experiments, but the reactions were severe in the Sussex cattle and one died despite treatment. Twenty-nine immunized animals and 10 controls first experienced a mild infection, starting about 15 days after their arrival at the farm. Ten of the immunized animals and four controls had schizonts in peripheral lymph nodes for variable periods; one third of those had pyrexia. Nymphal Rhipicephalus appendiculatus ticks applied to three of the reacting immunized calves transmitted Theileria taurotragi to two animals and T. parva to a third. A second Theileria infection, due to T. parva bovis, was detected shortly after the first one. Schizonts were detected in seven out of 10 controls. Pyrexia was more severe and prolonged. Two of the controls died of theileriosis. At the same time schizonts were seen in three immune animals and eight of them had short periods of pyrexia. Intercurrent infections with Babesia bigemina, Borrelia theileri and Eperythrozoon were detected and may have contributed to the fever. Tick infestations were low during the exposure. In the second year of exposure, four out of eight new control animals had severe reactions, and one died. None of the immunized animals became ill, but one animal from the first year control group, which had not reacted previously, had clinical theileriosis. It is concluded that immunization provided an effective protection against field challenge.

Animals↗

PubMed1990

The effects of bovine tick resistance on the susceptibility of Hyalomma anatolicum anatolicum to infection with Theileria annulata (Ankara).

Two Bos taurus calves were made resistant to tick infestation by exposing them to approximately 500 rabbit-reared nymphs of Hyalomma anatolicum anatolicum twice at a 2-week interval. These two calves, together with a tick-susceptible control calf, were inoculated with a stabilate of Theileria annulata (Ankara). Patent infection resulted in all three calves. Seven-hundred and fifty gerbil-reared nymphs were then applied on each of these calves as well as another tick-susceptible calf that was Theileria free. This infestation was carried out on Day 8 post-inoculation. Ticks that dropped on Day 13 post-inoculation were examined to note the development of T. annulata in them and the histological changes that occurred in the gut and salivary glands. During the second phase of feeding, the gut epithelia of the ticks from the tick-resistant calves were less active. There were no notable differences in the characteristics of the developmental stages of T. annulata between the ticks from the tick-resistant calves and those from the susceptible calf. However, ticks from one calf that acquired a higher level of tick resistance were significantly less susceptible to infection by T. annulata. Bovine tick resistance therefore compromises the vector capacity of H. a. anatolicum and this may be of epidemiological significance in the endemic areas of tropical theileriosis.

Animals↗

PubMed1990

Treatment of experimentally induced cytauxzoonosis in cats with parvaquone and buparvaquone.

The efficacy of parvaquone (Clexon) and buparvaquone (Butalex) in treating experimentally induced feline cytauxzoonosis was explored. Domestic cats were inoculated subcutaneously with blood from a cat infected with Cytauxzoon felis and treated daily with either 20 or 30 mg kg-1 parvaquone, or 5 or 10 mg kg-1 buparvaquone, beginning on either the first day parasites were detected in peripheral blood, or 2 days after the onset of parasitemia. Fifteen cats were treated and all but one died due to the infection. Unexpectedly, one of two non-treated, infected control cats survived. Although parvaquone and buparvaquone are the treatments of choice for a related hemoprotozoan parasite causing theileriosis in African cattle, wer concluded that at the dosages and regimes tested, these drugs are not effective treatments for feline cytauxzoonosis. Blood from the two surviving cats was inoculated into naive cats and in these animals clinical disease or death were not observed. The latter two naive recipient cats were then inoculated with a lethal dose of viable, frozen C. felis and both died, thereby indicating that blood from surviving cats did not induce an infectious state that resulted in immunity. The two cats that survived the acute infection were subsequently challenged with a lethal inoculum of C. felis; they showed no clinical signs of cytauxzoonosis and were obviously immune to reinfection.

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